Time delay mechanism



Jan. 6, 1942. HQA. TRIPLETT TIME DELAY MECHAN-ISM Original Filed Aug. 20, '1936 3 Sheets-Sheet 1 Jan 6, 1942 H. A. TRIPLETT 2,268,912

TIME DELAY MECHANISM Original Filed Aug.- 20, 1936 y 3 Sheets-Sheet 2 Jan. 6, H A TRlPLETT 2,268,912

` TIME DELAY MECHANISM Original Filed Aug. 20, 1936 3 Sheets-Sheet 3 Patented Jan. 6, 1942 Hughl A,- Triplett, W

Schweitzer a: Conrad, Inc.,

ilmette, Ill., assignor to Chicago, Ill., a

corporation otDelaware Original application August 20, 1936, Serial 12 claims.

My invention relates to time delay mechanisms. This application is a division of my copending application, Serial No. 96,928, filed August 20, 1936, and assigned to the assignee of this application.

In my copending application, Serial No. 694,584, filed October 21, 1933, now Patent No. 2,087,744, and assigned to the assignee of this application, I have disclosed a repeating cutout fuse device which is capable of restoring a circuit connection a predetermined time after one fuse device blows. In the particular embodiments of the invention illustrated, provision is made for reclosing the circuit twice after the first fuse device blows. The iirst two fuse devices comprise completely enclosed fuse and transfer switchv assemblies which are arranged for unitary mounting on a. suitable base- Each of these fuse devices comprises a fusible element which is arranged to hold a switch contact out of engagement with a cooperating contact as biased into circuit closing. position by a tension spring. As soon as the fusible element blows, the contact member is released for movement. under the influence of the tension spring.

Divide July 28, 1937, Serial d and this application (Cl. G-126) after the fuse device has blown that would cause i a break down. The liquid dielectric in the housing also assists in preventing the formation of the creepage path.

In this same application I have also disclosed a reclosing fuse device .of the air break type.

In this device a solid arc extinguishing material may be employed for extinguishing the arc. However, no liquid dielectric is employed. In

f this device the housing is formed of fiber. Such a device has the disadvantage that the fiber housing is opaque and therefore it is not possible to visibly inspect the interior of the fuse device as is the case when a glass housing is employed. Another disadvantage lies in the fact that a creepage path is liable to develop between the terminals of a Iblown fuse device which is provided with a ber housing. It is desirable to avoid these two disadvantages and to provide a means for indicating that a fuse device having a fiber housing has blown and also to remove it v from the circuit so that a creepage path cannot Its movement at first is rapid in order to make o certain that the arc is extinguished between the terminals of the fusible element. A liquid arc extinguishing medium is provided for assisting in A extinguishing the arc. After moving to a predetermined positiona time delay mechanism is encountered which slows up the movement of the contact arm to provide an appreciable interval between the blowing of the fusible element and the connection of the next fuse device into the circuit.' In one embodiment of the invention the contact member is arranged to pick up a piston which moves through a restricted portion of the fuse tube in the liquid, thus taking the form of an hydraulic escapement device. When the piston passes the constricted portion of the tube, it is free to move through the arc extinguishing liquid andconsequently the contact member is permitted to engage the fixedA contact member with a quick action, under the influence of the tension spring.-

In this fuse device a glass housing is provided which not only permits visual inspection of the condition of the fuse device but also provides a desirable dielectric between its terminalsafter it has blown. A casual inspection will then reveal whether or not the fusedevice has operated and should be refused. Since the housing is oi' glass, there is little likelihood that a creepage path will be developed between the terminalsdevelop.

Some power line operators require that the entire fuse housing be removed from the circuit in the event that it blows. Thus, the change in position of the fuse housing indicates at once that it has blown. Another advantage of this type of construction lies in the fact that no creepage path is left between the fuse terminals over which a ashover or breakdown might occur. In order to obtain these two advantages, together with certain other advantages in cost and ease in re-fusing, it has been proposed to rotatablymount the iirst two fuse devices, at least, and to release them for rotation on blowing, either under the .influence of gravity or uder the influence of a spring, to clear the circuit and at the same time operate a transfer switch for connecting the next fuse device in the circuit.

In the copending application of Allan Ramsey, Serial No. 740,057, filed August 16, 1934, and assigned to the assignee of this application, a repeating or reclosing cutout of the drop out type is disclosed comprising three fuse devices mounted on a common base. These fuse devices are rotatably mounted at their bases. Under normal operating conditions the fuse devices are secured in a substantially upright position and one of them is connected in an electric circuit while the other two are disconnected from the circuit. In the event that a fault occurs on the' circuit. the fuse device connected therein blows in the customary and well known manner and opens up fuse device in the circuit in base of the first and second fuse devices, each having an operating arm which is disposed in the path of the fuse device as it rotates after blowing. This switch is arranged to connect the next yorder to automatically ,restore the service. In like manner, if the second fuse device blows, it will operate the switch associated therewith to connect the third fuse device in the circuit. When the third fuse device operates, the circuit is completely cleared and no further automatic reestablishment thereof takes place. It is Ithen necessary to refuse and manually reset the fuse apparatus beforel the circuit can be restored 'to normal operating conditions.

In many instances it is undesirable to immediately reestablish the circuit. That is, the time which elapses after the first fuse device blows before the circuit is completed through the sec- `ond fuse device may be insufficient. Such 'operating conditions may occur where there is a temporary fault on the circuit caused, for example, by the accidental short circuiting of the conductors as a result of a high wind. Sometimes a branch will momentarily short circuit the conductors, but it may be immediately removed. In such instances, it is undesirable to reclose the circuit through la second fuse device while the fault condition still persists. To reclose on the fault would merely result in the blowing of the second fuse device immediately, with the result that the chances for automatically reestablishing the circuit are somewhat more limited.

In the copending application of Ramsey, no specific time delay is introduced between the operation of one fuse device and the connection of another in the circuit except that which is inherent in the time requiredvfor the blown fuse device.

to fall from its normal position through whatever frictional resistance may be encountered. While the time interval, which is inherent in the falling of a fuse device, may be suiclent for ordinary purposes, there are some cases where it is desirable to provide a longer time interval.

Any time delay mechanism which is employed to provide the desired time interval between the blowing of 'ne fuse device and the connection of the next one in `the circuit must be of such construction that its operating characteristics will not be changed regardless of the length of time that it is in service. For example, a reclosing fuse device may be installed on a line.

and not called upon to operatefor several months or even years. Nevertheless, after one month or after one year the time delay mechanism must be capable of providing the required time interval. Therefore, it must be so constructed that it will be 4unaifected by the weather, particularly `variations in temperature.

Accordingly, the object of my invention, generally stated, is to provide a time delay mechanism for repeating or reclosing fuses or cutouts which shall be simple and eiicient in operation and which may be readily and economically manufactured and installed.

'I'he principal object of my invention is to providea predetermined time delay between the operation of a fuse device and the reestablishment of the circuit through a second 'fuse' device.

An important object of my invention is to provide for delaying the operation of a transfer vide for hermetically sealing a time delay device arranged and constructed to provide a predetermined time delay between the blowing of one fuse device and the restoration of the circuit through another fuse device to assure permanency and reliability of operation.

A specific object of my inventionv is to provide a hydraulic escapement device hermetically sealed by a iiexible bellows for delaying the reestablishment of an electric circuit through a second fuse device after a first fuse device has blown.

Other objects of my invention will, in part, be-r obvious and, in part, appear hereinafter.

My invention, accordingly, is disclosed in the f embodiment hereof shown in the accompanying drawings, and it comprises the feature of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the appended claims.

For a more vcomplete understanding of the nature and scope of my invention reference may be had to the following detailed description, taken in conjunction with the accompanying drawings' in which:

Figure 1 is a view, in front elevation, illustrating a concrete embodiment of my invention, one of the fuse devices being shown in the position to which it rotates after it has blown;

Figure 2 isa sectional View taken along the line 2-2 of Figure l; f

Figure 3 is a view taken substantially along the line 3-3 of Figure 1, the details of construction of the transfer switch being omitted to more clearly illustrate the arrangement of the time delay mechanism;

Figure 4 is a sectional view, at an enlarged scale, showing the details of construction of the According to my invention as herein disclosed,

I have provided a hermetically sealed hydraulic escapement device for the first andsecond fuse devices of a three-unit repeating cutout, for providing a predetermined regulatable time interval after one fuse device blows before the next fuse device is connected to reestablish the circuit. The hydraulic escapement device comprises a cylinder which is fastened to a suitable support and a piston which is connected to a lever that is arranged to be engaged by a roller carried by a stop pawl on the fuse device. The cylinder is filled with a suitable non-freezing liquid and the piston is provided with a valve which, while opposing the movement of the piston in the cylinder in one direction, readily permits movement thereof in the opposite direction. A needle valve is provided in the piston for regulating the speed of its movement into the cylinder, thereby providing a regulatable time interval for the device. A

The stop pawl is rotatably mounted on the fuse vtube clamps and cooperates with the hydraulic of thedrawings, it will beobserved that the reference character I designates, generally, a"v

repeating fuse cutout comprising fuse devices II, I2 and I3, which are arranged to engage at their upper ends with contact assemblies I4. The contact assemblies I4 are commonly mounted on a suitable bus connector I5 which has connected thereto, a terminal I6 for connection with a circuit. The bus connector I5 is mounted on an insulator I1 which, in turn, is mounted on a support channel I 8 that may be mounted on a cross arm or thelike for installation purposes. The fuse devices II, I2 and I3 are individually rotatably mounted on insulators I9 at the lower ends thereof, which are carried by a cross strap mounted at the lower end of the channel I8. A suitable latching mechanism, illustrated generally at 2l, is provided for latching the fuse devices in position and for manually removing them therefrom, if desired. Resilient bumpers 23, preferably formed of rubber, are provided for absorbing the impact of the fuse devices on falling thereof after they have been blown.

The fuse devices II and I2 are provided with transfer switches, shown generally at 24, for successively shifting the circuit from one fuse device to the next one in order to reestablish the circuit to provide continuity of service. Each of the transfer switches 24 comprises a stationary enclosed contact member 25 depending from a suitable arm 26 which is carried by the next fuse device, as illustrated. A switch arm 21, carried by a switch operating lever 28, is provided for engaging the stationary contact member 25. A transverse pin 29, carried by the switch operating arm 28, is provided in the path of each of the fuse devices II and i2 for operating the transfer switch 24 individual thereto on movement thereof from the normal circuit closing position. A connector 30 is provided for establishing the necessary connection to the electric circuit. A contact finger 3| is provided near the lower end of each of the fuse devices for 'engagement with spring fingers 32 carried by the insulators I9 for connection therewith. The spring iingers 32 may serve also to bias the fuse devices to the open position in addition to the force of gravity when they are blown. It will be understood that the circuit extends from the connector I6 to the contact assemblies i4 and that normally it extends through the fuse device II to the connector 30. On blowing of the fuse device I! in response to a fault, the circuit is reestablished throughl the fuse device I2 on operation of the iirst transfer switch 24 by the fuse device II. In like manner, on operation of the fuse device I2, the circuit is extended to include the fuse device I3 on operation of the second transfer switch 24. The foregoing repeating fuse apparatus is essentially as that disclosed in the copending application of Ramsey, referred to hereinbefore. Since a detailed description of the various parts of the apparatus is fully set forth in this copending application, and further, since it forms no part of my invention, a further description thereof will not be set forth herein.

As has been set forth hereinbefore, it is desirable to provide a reguiatable time interval after one of the fuse devices blows, before the next fuse device is connected ,to reestablish the circuit. This time delay may be introduced either to delay the movement of the fuse device from its normal position to the full open position, or the time delay may be introduced in conjunction with the operation of the transfer switch itself.

According to the exemplification of the invention herein disclosed, I have provided for delay; ing the movement of the fuse device. However, it will be understood that the time delay may be applied directly to the functioning of the transfer switch itself, without regard to the operation of the fuse device in moving from one position to another.

As shown more clearly in Figures 2 and 3 of the drawings, the fuse device I2 is provided with a tube clamp 35 near-itsl lower end, on which is pivotally mounted al stop pawl 36 having an arm extending therefrom, the movement of whichl is limited by a stop pin 31.v It will be understood that the fuse device il is provided with a similar tube clamp 35 and associated time delay mechanism. A coil spring 38 is provided for normally biasing the stop pawl 35 to the position shown in Figure 3 of the drawings. At the lower end of the stop pawl 36 a roller 39 is carried for engaging with the upper cam surface of a check lever 40 which is pivotally mounted at its rear end on a mounting bracket 4I which may be mounted, by any suitable means, on the insulator i9. Mounted between a pin 42 carried by the check lever 40 and a pin 43 carried by the mounting bracket 4I, is a hermetically sealed hydraulic escapement device, illustrated generallyat 44.v The hydraulic escapement device 44 is arranged to retard the downward movement of the check lever 40 as it is moved downwardly by the falling of the fuse device i2, for example.

A slight movement of the fuse device I2 can take place without causing any downward movement of the check lever 40 because of the provision of the rotatably mounted stop pawl 35 and the stop pin 31. As soon as the fuse device blows it is released at its upper end and begins to rotate in a clockwise direction. The stop pawl 36 rotates with it until it engages the stop pin 31, at which time it is no longer free to rotate relative thereto. A downward thrust is then applied by the roller 39 to the check lever 40 to operate the hydraulic escapement device 44. The roller 39 as carried by the fuse device I2 follows the contour of the cam surface of the check lever 40. A

Because of the provision of the rotatably mounted stop pawl 36 and the cam surface on the check lever 40, the retarding effect of the escapement device 44 is available only when the fuse device I2 rotates in a clockwise direction in response to the occurrence of a fault while, when it is moved in the opposite direction, as when it is replaced, no retarding'force is provided. This action is due to the fact that the stop pawl 36 is capable of rotation when the fuse device I2 is rotated' in a counterclockwise direction, resulting in substantially no pressure being applied to the escapement device 44. This operation is desired because of the fact that relatively high pressures are developed in the hydraulic escapement device 44. When the fuse device I2 is restored to its normal position by an operator, there is a tendency to push it quickly and positively.` As a result, if the hydraulic escapement ear 5i, with a suitable transverse aperture forv connection to the pin 43. A cylinder 52 is centrally located in the upper surface of the base 50 and is secured thereto by pins 53. Cooperating 1 with the cylinder 52 is a piston 54 that is threadably mounted in a cap 55 having an upstanding ear 56 with a suitable aperture through which the pin 42 projects. The piston 54 is provided with a piston head 51 at its lower end, having piston rings 58 to provide a seal between the outer periphery thereof' and the inside walls of the cylinder 52.

In order to readilyipermit movement of the piston 54 in the up direction, an aperture 59 is .provided in the piston head 51 which` i`s arranged to be closed by a valve member 50. A compression spring 5I, disposed between the valve mem` ber 50 and a retaining washer 62, secured by peening or otherwise to the piston head 51,-is

provided to close the aperture 55 when the piston 54 is moved downwardly and to permit its being opened when it is moved in an opposite direction. It will be understood that the cylinder 52 is lled with a suitable liquid, such as glycerine and alcohol, to the level-indicated, and that by virtue of the downward movement of the piston 54 the biasing force of the spring 5! is Aaided by the liquid -in causing the valve member 55 to cover the'aperture 59.

A second aperture 63 is provided in the piston head 51, as illustrated, the ow of liquid through f -which is regulated by a needle valve 54. By suitably adjusting the needle valve 54 it will be apparent that the speed of downward movement of Ithe piston 54 may be varied, depending upon whether a large or small amount of the liquid is permitted to flow through the aperture 53.

With a view to hermetically sealing the cylinder 52 and the piston for the purpose of preventing escape of the liquid regardless of the length of time the device is inservice and for providing flexibility between the base 50 and the cap 55, a Sylphon bellows 65 is provided, the lower end of which is secured, by soldering or otherwise, to the base 50. The upper end of the bellows B5 is secured to a collar 66 which depends from and is secured to the cap 55, as by screws, or any other suitable means. Surrounding the lower end of the bellows 55 is a lower housing member 68 which is secured by pins 59 to the base 50. An upper housing member 10, having a telescopic t with the lower housing 58, is provided around the upper portion of the bellows 55. The upper housing 18 is secured by pins 1| to aring 12,

j having a pressed t with the collar `56. A compression spring 13 is provided between the upper end of the lower housing 58 and the under surface of the ring 12 for normally biasing the piston 54 to the upper position as shown in the drawings.

A modified form of thev hydraulic escapement device is shown in Figure 5 of the drawings. As there illustrated, the cap 551s secured to a suitable/ ring that is secured by the pins 1I to drawings.

the upper housing member 10 and to the underside of which the Sylphon bellows 55 is attached Depending from the cap 55 is a piston 16 having at its lower end a piston head 11 provided with transverse apertures 18 which are covered by a movable ring 19 to retard the move'- ment of the piston i6 when itis moved downwardly through the liquid in the cylinder 52. The washer 19 cooperating with the apertures 18 forms, in effect, a check valve which is closed when the piston 18 is moved downwardly, thereby retarding its movement in this direction, and which is open when it is moved in the opposite direction to permit free upward movement under the inuence of the compression spring 13. A small aperture is centrally located in the piston head 11 and a needle valve, in the form of a sharp tipped screw 8i, threadably mounted in the center of the piston 15, as illustrated, is arranged to control the ow of the liquid therethrough as the piston head 11 is moved downwardly. It will be observed that the liquid flows upwardly through the aperture 85, as controlled by the position of the needle valve 8|, and out through a transverse aperture 82 which l is located just above the piston head 11.

In Figure 6 I have shown another embodiment of the hydraulic escapement mechanism which may be employed in practicing the present in-jl vention. As there illustrated the escapement device 44 is provided having essentially the same construction as shown in detail in Figure 4 of the In this instance, however, the check valve comprising the valve member 65. and the spring 6I is omitted together with the needle valve 54. The piston 54 and the piston head 51 serve merely as a guiding means in the cylinder Associated with the device 44 is a chamber, shown generally at 84, which comprises a ilexible bellows 85 that is closed at its upper end by a cap 86 and at its lower end by a base member 81. It will be understood that the flexible bellows 85 is secured to the cap 35 and the base 8T byl soldering or the like in order to provide a hermetically sealed chamber. The chamber 84 Vis mounted on a support member 88 which may be secured by bolts, not shown, to the base member 50 of the escapement device 44. The support member 88 is provided with a passageway 99that connects with a passageway 90 in the base member 5l?, as illustrated. The base member 81 is provided with a restricted opening 9| with which a needle valve 92 cooperates-to control the'ow of liquid therethrough. Both chambers formed by the flexible bellows 65 and 85 are lled with a suitable non-freezing liquid, such as a mixture of alcohol and glycerine.

In this embodiment of my invention when the lever 40 is moved downwardly by the falling of the fuse device Il, for example, the Ycap 55 of the device 44 is moved downwardly, compressing the flexible bellows 55 and forcing the liquid to flow through the passageways 90 and 89 and the restricted opening 9| into the chamber 84 formed by the exible bellows 85. Since this chamber is lled with liquid, it expands upwardly at a speed depending upon the sizeof the open- -ing 9| as controlled by the position of the needle valve 92.l When the force causing the downward movement of the cap 55 is relieved, as by the to contract and to force a part of the liquid back an intermediate wall between the two chambers through which the liquid ows as well as providing a common support therefor.

In order to regulate the ow of liquid into the chamber 84 it is necessary to remove the cap 86 and rotate the needle valve 92 in the desired direction. It is desirable to provide for externally adjusting the time interval and for this purpose the construction illustrated in Figure '7 of the drawings may be employed in conjunction with the device 64 and the chamber 84.

As illustrated in Figure '7 theV device M and.

the chamber 84 are mounted on a common support member 95 having a transverse passageway 9B therethrough which opens into the chamber 84. A boss 91 is integrally formed underneath the support member 95 and has an angularly disposed passageway 98 therein, the outer end of which is closed by a plug 99 to permit the introduction of the liquid into the chambers, as will be readily understood. The passageway 98 opens into a small chamber |08 which. is formed by the downwardly extending lips of the boss 91, as illustrated. A needle valveA |8| is provided for regulating the flow of the liquid from the passageway 90 in the base 5|) at the bottom of the chamber formed by the flexible bellows 65 into the small chamber |88. Aflexible diaphragm |82 is suitably secured to the downwardly extending anges of the boss 91 and tothe needle valve |8| to hermetically seal the enclosure. An adjusting screw |83 permits external operation of the needle valve |8|, thereby rendering unnecessary the dismantling of any of the sealed chambers to efect the adjustment. Y

With a View to permitting the restoration of the escapement device to its normal position without encountering the time delay provided by the needle valve |8|, a check valve, shown generally at |05, is provided in the common support member 95. The check valve |85 cooperates with a passageway |86 which extends through the base 58 and it comprises an externally "threaded retaining member |81 which is provided with a ball |88 biased against a centrally located aperture by means of a compression spring |89. When the cam lever 48 is moved downwardly the pressure of the liquid in the bellows S5 forces the ball |88 to seal the small aperture in the retaining member |8|, thus permitting the liquid to fiow at a speed depending solely upon the adjustment of the needle valve |8|. When the pressure applied to the cam lever 48 is released, the liquid flows back to its normal condition. The pressure` developedon the return flow is suilicient to move the ball |88 upwardly against the biasing force of the spring |89 and, therefore, it returns to the iiexible bellows B5 with a minimum of delay. In other words, the check valve |85 bypasses the needle valve |8| to permit the restoration of the escapement device to its norma-l condition with a minimum of delay. It

' will, of course, be obvious that the check valve |85 may be entirely dispensed with and the liquid will then be permitted to return to its normal conditionafter the elapse of a considerable interval, as controlled by the setting of the needle valve |8|.

Since certain further changes may be made in the above constructions, and different embodiments ofthe invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative, and not in a limiting senser.r

I claim as my invention:

l. In a reclosing fuse device of the drop out type, in combination, a time delay device for determining the time interval between the vblowing ofone fuse and the closing of a transfer switch to reestablish the. circuit through the next fuse, comprising a cylindrical housing having an end wall and a relatively movable wall, the relatively movable wall being provided with a restricting passage through which a uid is forced to iiow by relative movement between it and said end wall.

2. In a reclosing fuse device, in combination, a time delay device for determining the time interval between the blowing of one fuse and the closing of a transfer switch to reestablish the circuit through the next fuse, comprising a housing having end walls and a cylinder with a piston slidable therein forming a dividing wall, the

dividing wall being provided with a restricting l -passage through which a fluid is forced to flow by relative movement between the dividing wall and one end wall, and resilient means for restoring said timing device to its normal condition when the force'causing said relative movement is relieved.

3. In a reclosing fuse device, in combination,

I a time delay device for determining the time inand one end wall, and resilient means for restoring said timing device to its normal condition when the force acting onv said dividing wall is relieved.

4. In a reclosing fuse device, in combination, a time delay device for determining the time interval between the blowing of one fuse and the closing of a transfer switch to reestablish the circuit through the next fuse, comprising a housing having end walls and a cylinder with a piston slidable therein forming a dividing wall, the dividing wall being provided with a restricting passage through which a fluid is forced to iiow by relative movement between the dividing wall and one end wall, and resilient means for restoring said timing device to its normal condition when the force acting on one of said end walls is relieved.

A hydraulic escapement device for determining the time between the blowing of one fuse of a reclosing fuse device and the closing of a transfer switch to reestablish the circuit through the next fuse, comprising, in combination, a cylinder closed at one end, a piston slidably mounted in said cylinder. a check valve in said piston disposed to be closed when it is moved toward said closed end and to be opened when moved in the opposite direction, an opening eX- tending transversely throughsaid piston, and a needle valve disposed to cooperate with said opening.

6. A hydraulic escapement device for determining the time between the blowing of one fuse of a reclosing fuse device and the closing of a transfer switch to reestablish the circuit through the next fuse, comprising, in combination, a ycylinder closed at one end, a iiuid in said cylinder, a piston slidably mounted in said cylinder for movement through said iiuid, a check valve in said piston disposed to be closed when it is moved toward said closed end for retarding movement through said fluid and to be opened when it is moved in the opposite direction, an opening extending axially through said piston, a needle valve cooperating with said opening for regulating the flow of iiuid therethrough when said piston is moved toward said closed end, and a ilexible bellows forming a sealed housing around said cylinder and piston.

7. A hydraulic escapement device comprising, in combination, a cylinder closed at one end, a

liquid in said cylinder, a piston in said cylinder,

inder to prevent binding therebetween, and a fiexf ible bellows sealed at one end to said cylinder and at the other end 'to said piston to form therewith a fluid tight housing.

9. A hydraulic escapement device comprising, in combination, a cylinder closed at one end, a liquid in said cylinder, a piston in said cylinder having a restricted passageway to permit said liquid to flow therethrough on relative movement of said piston and said cylinder, a exible bellows sealed at one end to said cylinder and atvthe vother end to said piston to form therewith a iiuid tight housing, and spring means interposed between said cylinder and piston in such man ner as to bias them relative to each other.

10. A hydraulic escapement device comprising, in combination, a. cylinder closed at one end, a liquid in said cylinder, a piston slidably mounted-in said cylinder and having a restricted passageway therein to permit said liquid to ow l therethrough on movement of said piston toward the closed end of said cylinder, a exible bellows sealed at one end to said cylinder and at the other end to said piston to form therewith a uid tight housing, and a coil spring disposed around said flexible bellows and interposed between said cylinder and ypiston in such manner as to bias the latter away from said closed end of the former.

11. A hydraulic escapement device comprising, in combination, a cylinder closed at one end, a liquid in said cylinder, a piston slidably mountedin said cylinder and having a restricted passageway therein to permit said liquid to flow therethrough on movement of said piston toward the closed end of said cylinder, a flexible bellows sealed at one end to said cylinder and at the other end to said piston to form therewith a uid tight housing, and a pair of cylindrically shaped members secured to said cylinder and piston respectively around said flexible bellows and disposed to telescope with each other.

12. A hydraulic escapement device for retard- 'ing relative movement between two members one of which is mounted for rotary movement relative to the other comprising, in combination, a cylinder closed at one end and adapted to be rockably mounted on one of said members, a y

liquid in said cylinder, a pistn in said cylinder adapted to be rockably mounted on the other of said, members, there being a restricted passage- Way to permit said liquid to flow past said piston on relative movement of said members, and a flexible bellows hermetically sealing said cylinder and piston.

HUGH A. TRIPLE'I'I. 

